Certain well-known narcotic analgesics belong to the class of 4,5.alpha.-epoxymorphinan compounds which have the following basic ring system in which the atoms are numbered as indicated: ##STR2##
The two most familiar compounds of this class are morphine and its 3-methyl ether, codeine, with the structures indicated below: ##STR3##
When the 6-hydroxyl group of each of these compounds is oxidized to an oxo group, the compounds conveniently are referred to as morphinone and codeinone, respectively. When the N-methyl groups of the latter compounds are replaced by other substituent groups they may be referred to as N-substituted normorphinones and norcodeinones, respectively. There are two types of nomenclature commonly used for describing compounds herein. The trivial names, such as morphine or morphinone, are widely accepted and used for the sake of brevity and clarity. The Chemical Abstracts nomenclature is preferred and is used wherever precision is needed.
Compounds having the basic morphine or morphinan nucleus, either with or without the 4,5.alpha.-epoxy bridge, are of interest because they may act as strong analgesics, and research into this class of compounds continues in laboratories throughout the world.
Bentley and Hardy disclose in Journal of the American Chemical Society, 89:13, Pp. 3267-73, certain Diels-Alder adducts of thebaine having the formula: ##STR4## where R is methyl or phenyl. It is stated that these compounds possess analgesic activity. This 6,14-endoethenotetrahydrothebaine (oripavine) series of analgesics, as disclosed by Bentley and his coworkers, differs from the compounds of the present invention by the presence of the 6,14-etheno bridge in the oripavines which alters the stereochemistry of the molecules. Furthermore, while both are substituted at the 7-position, the oripavines contain a methyl ether of a tertiary alcohol at C-6 whereas the present compounds are unsubstituted at the 6-position and contain a double bond at C.sub.6 -C.sub.7.
U.S. Pat. No. 4,347,361 (issued Aug. 31, 1982) discloses 4,5.alpha.-epoxy-3-methoxy-7-(1-hydroxyalkyl)-morphinan-6-one compounds of the formula: ##STR5## where R.sub.1 is H or methyl, R.sub.2 is straight or branched chain alkyl of from 1 to 10 carbon atoms, aryl, substituted aryl or arylalkyl and R.sub.3 is a straight chain alkyl group of 1 to 4 carbon atoms. These compounds differ from those claimed herein in several respects including the presence of a 1-tertiary alcohol rather than a 1-secondary alcohol at the 7-position.